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\t\t\t\t\t\t08\/08\/2024<\/span> ESA\u2019s star-surveying Gaia mission has again proven to be a formidable asteroid explorer, spotting potential moons around more than 350 asteroids not known to have a companion.<\/p>\n<\/div>\n Previously, Gaia had explored asteroids known to have moons \u2014 so-called \u2018binary asteroids\u2019 \u2014 and confirmed that the telltale signs of these tiny moons show up in the telescope\u2019s ultra-accurate astrometric data. But this new finding proves that Gaia can conduct \u2018blind\u2019 searches to discover completely new candidates, too.<\/p>\n<\/p><\/div>\n \u201cBinary asteroids are difficult to find as they are mostly so small and far away from us,\u201d says Luana Liberato of Observatoire de la C\u00f4te d\u2019Azur, France, lead author of the new study. \u201cDespite us expecting just under one-sixth of asteroids to have a companion, so far we have only found 500 of the one billion known asteroids to be in binary systems. But this discovery shows that there are many asteroid moons out there just waiting to be found.\u201d<\/p>\n If confirmed, this new finding adds 352 more binary candidates to the tally, nearly doubling the known number of asteroids with moons.<\/p>\n<\/p><\/div>\n Asteroids are fascinating objects, and hold unique insights into the formation and evolution of the Solar System. Binaries are even more exciting, enabling us to study how different bodies form, collide and interact in space.<\/p>\n Thanks to its unique all-sky scanning capabilities, Gaia has made a number of important asteroid discoveries since its launch in 2013.<\/p>\n In its data release 3, Gaia precisely pinpointed the positions and motions of 150 000+ asteroids \u2014 so precisely that scientists could dig deeper and hunt for asteroids displaying the characteristic \u2018wobble\u2019 caused by the tug of an orbiting companion (the same mechanism as displayed here for a binary star). Gaia also gathered data on asteroid chemistry, compiling the largest ever collection of asteroid \u2018reflectance spectra\u2019 (light curves that reveal an object\u2019s colour and composition).<\/p>\n<\/p><\/div>\n The 150 000+ orbits determined in Gaia\u2019s data release 3 were refined and made 20 times more precise as part of the mission\u2019s Focused Product Release last year. Even more asteroid orbits are anticipated as part of Gaia\u2019s forthcoming data release 4 (expected not before mid-2026).<\/p>\n \u201cGaia has proven to be an outstanding asteroid explorer, and is hard at work revealing the secrets of the cosmos both within and beyond the Solar System,\u201d says Timo Prusti, Project Scientist for Gaia at ESA. \u201cThis finding highlights how each Gaia data release is a major step up in data quality, and demonstrates the amazing new science made possible by the mission.\u201d<\/p>\n<\/p><\/div>\n ESA will further explore binary asteroids via the forthcoming Hera mission, due to launch later this year. Hera will follow up on NASA\u2019s DART mission \u2014 which collided with Dimorphos, a moonlet orbiting the asteroid Didymos, in 2022 as an asteroid deflection test \u2014 to produce a post-impact survey of Dimorphos. It will be the first probe to rendezvous with a binary asteroid system.<\/p>\n Gaia helped astronomers view the shadow cast by Didymos as it passed in front of more distant stars in 2022, an observing technique known as stellar occultation. The feasibility of this technique has been drastically improved by Gaia\u2019s asteroid orbits and ultra-precise star maps in recent years, proving the mission\u2019s immense value for Solar System exploration.<\/p>\n<\/p><\/div>\n The research used data from Gaia\u2019s data release 3, published in 2022, and is supported by the French national research agency (ANR)\u2019s \u2019GaiaMoons\u2019 project.<\/p>\n \u2018Binary asteroid candidates in Gaia <\/i>DR3 astrometry\u2019 by Liberato et al. (2024) is accepted for publication on 8 August 2024 in\u00a0Astronomy & Astrophysics. <\/i>doi.org\/10.1051\/0004-6361\/202349122<\/p>\n ESA\u2019s Gaia space telescope\u00a0was launched on 19 December 2013 and has been surveying the skies since 2014.\u00a0Read more about some of the telescope’s key achievements.<\/p>\n ESA\u2019s Hera mission is planned for launch in October 2024 and rendezvous with the Didymos-Dimorphos system in October 2026. Hera is also supported by the ACROSS project, which plans and performs stellar occultations of asteroids, including Didymos and Dimorphos. More on the Hera mission: <\/p>\n<\/p><\/div>\n
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\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nAn outstanding asteroid explorer<\/h2>\n
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\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nRendezvous with a binary asteroid system<\/h2>\n
\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nNotes for editors<\/h2>\n